TiO2 modified

Fig. 26. Reactions observed during the enantioselective hydrogenation of pyrone 1 catalyzed by Pd/ TiO2 modified by CD. After the fast hydrogenation resulting in 2 (target reaction), a considerably slower second hydrogenation reaction follows. Once lactone 3 is formed, it can undergo ring opening to yield the corresponding acid 4, which then adsorbs in various ways 5 on the catalyst support (48).

Photo)Electrocatalysis on Nanostructured TiO2 Surface Modified via Chalcogenide Materials... 

Hydration may modify the reactivity if the metallic sites are not available the acidity of the surface hydroxyl is less than that of the exposed metallic cations, H2O molecular adsorption on hydrated TiO2(H0) surface can result from these weak interactions (H-bonding with the surface hydroxyl groups)[22]Lindan, 1998 223], In this case, there is no direct interaction and the vibration frequencies should be recalculated on another model. Let us note that the basicity of the surface also varies in the case of Ti02(l 10) the lone pairs of a surface hydroxyl are less reactive than those of a naked surface oxygen for MgO it is the reverse the hydrated surface becomes more basic. 

The TiO2(110) surface can be modified to alter the surface chemistry of adsorbed methoxides. Recently Vohs et al. [73] have reported temperature programmed desorption studies of methanol on TiO2(110)-supported V2O5. Deposited monolayer films of vanadia converted some of the adsorbed methanol to formaldehyde and water, while multilayer films of vanadia on the TiO2(110) surface were found to be inactive for methanol oxidation. Furthermore, adsorption studies of formaldehyde indicated that formaldehyde production from... 

In one publication, an extensive morphological study was conducted on the effect of TiO2 on the morphology of crystallized PP and HDPE. The authors did not find any evidence of a modified morphology around the particles and concluded that spherulites grew until they were stopped by the surface of the filler unless the... 

However we consider that Fe203 behaves more like a modifier than an amphoteric and in our revised programme 1.5 x(FeO], 5) has been added to xjyj and x(Fe203) removed from xy. "Normalized" values Xq and xj7 and x are obtained by dividing the mole fractions, xq, xj and x by the term (1 + 2x(CaF2) + 0.5 x(Fe0i.5) + x(TiO2) +... 

An aluminum electrode modified by a chemically deposited palladium pen-tacyanonitrosylferrate film was reported in [33]. Vitreous carbon electrode modified with cobalt phthalocyanine was used in [34]. Electrocatalytic activity of nanos-tructured polymeric tetraruthenated porphyrin film was studied in [35[. Codeposition of Pt nanoparticles and Fe(III) species on glassy-carbon electrode resulted in significant catalytic activity in nitrite oxidation [36[. It was shown that the photocatalytic oxidation at a TiO2/Ti film electrode can be electrochemically promoted [37]. 

Scheme 10.15 Enantioselective hydrogenation of 4-hydroxy-6-methyl-2-pyrone over the CD-modified Pd/TiO2 and succeeding diastereoselective hydrogenation.

Munuera, G. at al.. XPS study of TiO2 surfaces modified by immersion in aqueous solutions. Mater. Sci. Forum, 25/26, 467, 1988. 

For the formation of ketones, a close examination of the data of Figure 2 reveals non negligible differences in the regioselecttivity for the different catalysts. In particular, the ratio of the amount of 2-one with respect to 4-one is higher for the modified Ti02. Since position 4 is less hindered, this behaviour may indicate that, for the formation of ketones, the interaction of methylcyclohexane with the surface is a more critical step with unmodified TIO2 than with derivatized T1O2. 

ETAS-IO(B) (Al2O3/TiO2=0.2), T=25°C, Hexadecylpyridinium chloride-modified montmorillonite. 

Fig. 11.19 STM images (acquired at bias of 1.0 V and set point current of 10 pA, size of 7.3 X 7.3 nm ) showing the photocatalyzed dissociation of methanol, (a) Bare TiO2(110)-l x 1 surface, (b) Surface with adsorbed CH3OH (0.02 ML), (c) After 10 min. irradiation by 400 nm light Dashed circles in (a), sites for CH3OH adsorption on Tis row. Cross, sites for CH3OH on Ov (labeled as BBOy in the figure). Black arrows in (c) indicate the four dissociated molecules after UV irradiation, (d) STM image after manipulation (0.4 V, 700 pA) of the dissociated molecule ml in the marked area of (c) (Modified with permission from Ref. [155]. Copyright 2010 the Royal Society of Chemistry)...

---